It is proposed to continue our kinetic and mechanistic studies pertaining to enzymic hydrations and hydrolyses with particular emphasis on erythrocyte carbonic anhydrases (carbonate hydrolyases EC 4.2.1.1). Proposed work uses Zn(II)-, Co(II)-, Mn(II)-, Cd(II)- and Ni(II)-carbonic anhydrases and exploits temperature jump, stopped flow, NMR, and ORD/CD techniques in the study of the elementary enzymic steps and their combination in the overall mechanism of hydration-dehyration in both H2O and D2O. Proposed work also exploits the remarkable versatility that these enzymes exhibit both with respect to their substrates and the variety of reactions which they catalyze. Other developments concern our biochemical studies of apo-carbonic anhydrase, of partial denaturation and reactivation, of sulfonamide inhibition, of active site modification, and of interaction with other proteins and with nucleic acids. We also propose to continue our kinetic and mechanistic studies of spinach carbonic anhydrase. Our earlier work has appeared in Biochemistry, J. Phys. Chem., J. Org. Chem., and J. Amer. Chem. Soc. BIBLIOGRAPHIC REFERENCES: Plant Carbonic Anhydrase. Hydrase Activity and Its Reversible Inhibition, Y. Pocker and Joan S. Y. Ng, Biochemistry, 13, 5116 (1974). Oxidative Cleavage by Lead (IV). II. The Role of Oxidant Modification in the Mechanism of the Base-Catalyzed Decarboxylation of Mandelic Acid by Lead Tetraacetate, Y. Pocker and B. C. Davis, J. Org. Chem., 40, 1625 (1975).